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Shielded cantilever with on-chip interferometer circuit for THz scanning probe impedance microscopy
Matvey Finkel1, Holger Thierschmann1, Allard J Katan1
1Kavli Institute of NanoScience, Department of Quantum Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
The Review of Scientific Instruments
|November 30, 2019
Summary
We developed a terahertz (THz) near-field cantilever for precise impedance measurements. This innovative probe enables quantitative analysis of materials at THz frequencies, overcoming previous technological limitations.
Area of Science:
- Physics
- Materials Science
- Electrical Engineering
Background:
- Terahertz (THz) near-field microscopy is crucial for material characterization.
- Existing THz probes face challenges with impedance mismatch and sensitivity.
Purpose of the Study:
- To develop a novel microstrip-based THz near-field cantilever for quantitative impedance measurements.
- To enhance readout circuit sensitivity using an on-chip balanced hybrid coupler.
Main Methods:
- Fabrication of a microstrip-based THz near-field cantilever.
- Integration of an on-chip balanced hybrid coupler for signal cancellation.
- Measurement of reflection coefficients with dielectric (Si, SrTiO3) and metallic (Au) samples.
- Finite element simulations for sensitivity determination.
Main Results:
- Quantitative impedance measurements at 0.3 THz.
- Demonstrated passive signal cancellation improving sensitivity.
- Distinct changes in reflection coefficients observed for different materials.
- Determined THz probe sensitivity below 0.25 fF.
- Integrated topography imaging capability.
Conclusions:
- The developed THz cantilever overcomes critical technological challenges in near-field microscopy.
- Enables shielded cantilever-based THz near-field microscopy for advanced material analysis.
- Paves the way for more sensitive and quantitative THz near-field measurements.
